Grit pad cleaner

ABSTRACT

A device for cleaning surfaces and the like which is comprised of a plate subjected to resonant sonic vibration and a highimpedance material, such as rubber, connected to and extending from the vibratory surface to contact the surface to be cleaned, forming an enclosure when so in contact, the enclosure being filled with a cleaning grit material which is caused to vibrate by the vibratory plate.

United States Patent [1 1 Bodine Mar. 27, 1973 GRIT PAD CLEANER [76] Inventor: Albert G. Bodine, 3877 Woodley Avenue, Van Nuys, Calif. 91406 [22] Filed: Apr. 12, 1971 [21] App1.No.: 133,068

Related US. Application Data [63] Continuation-in-p'art of Ser. No. 759,034, Sept. 11,

1968, abandoned, which is a continuation-in-part of Ser. No. 699,198, Jan. 19, 1968, Pat. No. 3,544,292, which is a continuation-in-part of Ser. No. 423,559, Jan. 5, 1965, Pat. No. 3,380,195.

[52] US. Cl. ..51/241 S, 51/59 SS, 51/170 R [51] IntfCl. ..B24b 31/06 [581' Field of Search...51/59 SS, 241 S, 7, 9, DIG. 11,,

[56] I References Cited UNITED STATES PATENTS 2,460,919 2/1949 Bodine ..51/59 ss 3,154,890 11/1964 Lemelson ..5l/59SS Primary ExaminerD0nald G. Kelly Attorneysokolski & Wohlgemuth [57] ABSTRACT A device for cleaning surfaces and the like which is comprised of a plate subjected to resonant sonic vibration and a high-impedance material, such as rubber, connected to and extending from the vibratory surface to contact the surface to be cleaned, forming an enclosure when so in-contact, the enclosure being filled with a cleaning grit material which is caused to vibrate by the vibratory plate.

4 Claims, 4 Drawing Figures PATENTEUHARZYIGR 3,7

sum 1 or 2 INVENTOR.

PATENTEDHARUIQR sum 2 or 2" INVENTOR. iv 6 49/! 63962 020 soiwzsu a We figgem um 50 GRIT PAD CLEANER This application is a continuation in part of application Ser. No. 759,034 filed Sept. 11, 1968 now abancloned, application Ser. No. 699,198 filed Jan. 19,

1968, now US. Pat. No, 3,544,292, and application Ser. No. 423,559 filed Jan. 5, 1965, now US. Pat. No.

3,380,195; application Ser. No. 759,034 being a continuation in part of application Ser. No, 699,198, and application Ser. No. 699,198 being a continuation in part of application Ser. No. 423,559. My US. Pat. Nos. 3,166,772 and 3,409,925 describe subject matter pertinent to the present application.

The .problem of removal of dirt, grime and the like from large surfaces such as the walls of buildings, ships, pipe lines, and other major structures, has been a long existing problem. Conventional methods and devices for effecting such cleaning include high-pressure steam apparatus and various forms of sand blasting devices. These prior methods are relatively time consuming and often 'involve large auxiliary equipment to achieve the high steam pressures or sand blasting pressure required.

Thus it is an object of the herein invention to-provide a new method for the rapid and expeditions cleaning of surfaces.

In Applicants earlier filed patent application Ser."

No. 274,975, filed Apr. 23, 1963 and now abandoned,

FIG. 4 is a side elevation view in partial secton of the embodiment of 3. v

In order to facilitate the comprehension of the operation of the device of the invention, it is helpful to make an analogy between an electrical resonant circuit and a mechanical resonant circuit. This type of an analogy is well known to thoseskilled in the art and is described, for example, in Chapter 2 of "Sonics by Hueter 'and Bolt, published in 1955 by John Wiley and Sons. In making such an analogy, force F is equated with electrical voltage E, velocity of vibration u is equated with electrical current i, mechanical compliance C,, .is equated with electrical capacitance C mass M is equated with electrical inductance L, mechanical resistance (such as friction) R is equated with electrical resistanceR. Mechanical impedance Z is equated with'electricalimpedance Z Thus, itcan be shown that if a member is elastically vibrated by a sinusoidal and its continuation-impart application, Ser. No.

699,198, filed Jan. 19, 1968, there is disclosed a novel method for the cleaning of metal parts and the like of foreign material. The'method disclosed in the prior earlier filed applications applies also to the removal of whole cores from casting and cleaning'of interior cavities of filaments or whiskers. These prior cases involve resonantly vibrating an'elastic system including acontainer enclosing the part to be cleaned. The container is filled with loose granular material, such as irregularly shaped grit. The resonantvibration of the container causes a rapid and expeditious cleaning of the part or parts therein. The herein invention is a further expansion of the initially discovered concept disclosed in the previously filed applications.

It has now been discovered, that the utilization of resonant sonic energy in combination with a loose granular material can be applied to large surfaces for the cleaning thereof, providing the sonic energy density is kept to a high value. The device of the herein invention utilizes an elastic membergenerally in the form of a plate, which is connected or affixed to an orbitingmass oscillator'such that it will resonantly vibrate. Surrounding the periphery of the plate and extending therefrom is a material of high impedance such as rubber or the like. The high-impedance material is then brought into contact with the surface to be cleaned and FIG. 1 is a pictorial presentation of a first embodiment of this invention applied to a surface to be cleanedj force F sinwt, on being equal to 21r times the frequency of vibration, that Z,,,=R,,,+j[mM(l/mC,,,)]= sinwt/v (1) Where mM is equal to l/wC a resonant condition exists, and the effective mechanical impedance Z,,, is

equal to the mechanical resistance R,,,, the reactive components wM and l/mC cancelling each other out. Under such a resonant condition, velocity of vibration u is at a maximum, effective power factor is unity, and

energy is most'efficiently delivered to the object being vibrated. It is such a high-efficiency resonant condition in the elastic system being driven that is preferablyutilized in the method and device of this invention to achieve the desired end results.

It is to be noted by reference equation (1 that velocity of vibration u is highest where impedance Z is lowest, and .vice versa. Therefore, a high-impedance load will tend to vibrate at relativelylow velocity, and vice versa. Thus, at an interface between high-and lowimpedance elements, a high relative movement results by virtue of such impedancemismatch which, as in the equivalent electrical circuit, results in a high reflected wave. Such an impedance mismatch condition between a conduit and the material being conveyed can be utilized to free the material from such conduit and effectively provide low friction between the two.

Just as the sharpness of resonance of an electrical circuit is defined as the Q thereof, and is indicative of the ratio of energy stored to the energy used in each cycle, so also the Q of the mechanical resonant circuit has the same significance and is equal to the ratio between wM and R,,,. Thus, high efficiency and considerable cyclic motion can be achieved by designing the mechanical resonant circuit for high Q.

Of particular significance in the implementation of I the method and device of this invention, is the high acceleration of the components of the elastic resonant system that can be achieved at sonic frequencies. The acceleration of a vibrating mass is a function of the square of the frequency of the drive signal times the amplitude of vibration. This can be shown as follows:

The instantaneous displacement y of a sinusoidally vibrating mass can be represented by the following equation:

The acceleration a of the mass can be .obtained by differentiating equation (2) twice, as follows:

The acceleration a thus is a function of Y times (211]) At resonance, Y is at a maximum and thus even at moderately high sonic frequencies, very high accelerations are achieved.

In considering equation (1), several factors should be kept in mind. Firstly, this equation represents the total effective resistance, mass, and compliance in a mechanical circuit, and these parameters are generally distributed throughout the system rather than being lumped in any one component or portion thereof. Secondly, the vibrating system often includes not only the conduit but surrounding components and the fluid material itself. Thus, it may be desirable to purposely add members exhibiting predominantly compliance C or mass M characteristics to balance out one or the other of these parameters to make for a resonant system. 'Thirdly, an orbiting-mass oscillator is utilized with the device of the invention, that automatically adjusts its output frequency to maintain resonance with changes in the characteristics of the load. Thus, in situations where we are dealing with a fluid material which solidifies in the process involved and thereby changes-its characteristics, the system automatically is maintained at optimum resonant operation by virtue of the lock-in characteristics of Applicant's unique orbiting-mass oscillators.

treated, there is a minimum power value per given volume of grit, below which effective action does not take place. Once the energy density within the grit is above this minimum threshold value for the particular surface condition, effective cleaning action will take place. In view of the foregoing, a practical size of sonic oscillator-resonator combination can be utilized in most jobs, providing provision is made to minimize the total volume of g'rit to be activated.

In the devices described in my aforementioned US. Pat. Nos. 3,380,195 and 3,544,292, particulate cleaning material is enclosedin a container and a part to be cleaned placed in this material and cleaned thereby, this by virtue of the resonant sonic energy generated by means of an orbiting-mass oscillator. Theoperation of these devices thus is analogous to that of the instant invention, the grit material being retained by a confining wall portion formed by an elastomeric member. The present application adds to the picture the high acoustical impedance nature of the confining wall which defines an enclosed volume when the cleaningmaterial is brought into contact with a surface to be cleaned and which prevents the direct coupling of the vibrational energy from the energy source to such surface;

further, the means for flowing the cleaning material.

through this enclosed volume to make for a portable tool suitable for cleaning surfaces.

Turning now to FIGS. 1 and 2, there is seen a fir'st embodiment of the herein invention. There is seen a resonating structure 11. Structure 11 is comprised of a suitable plate 13 or resonatorof an elastic material such as steel-Attached to plate 13 is elongated arm 15 which serves to acoustically couple a pair of orbitingmass oscillators 17 to the plate 13. As shown in the figures, the arni 15 can be actually integrally formed with plate 13 and cast as a single piece. The orbitingmass oscillators 17 are similar to those shown, for example, in US. Pat. No. 3,360,056, to the same inve'ntor, and are driven through pneumatic line 19. Affixed to the entire outer periphery of the plate and extending perpendicularly from the flat surface thereof is a wall 21 of a high-acoustic-impedance material such as rubber. When the device 11 is placed against a surface 23 to be cleaned, the elastomeric material'Zl forms a relatively tight flexible seal therewith and provides a cavity 25 between the surface to be cleaned and the plate 13 of the device. Inlet line 27 can direct grit particles 28 .into the cavity 25, while an outlet line 29 removes the spent grit and removed dirt. As shown in FIG. 2 particularly, avalve may be provided in the exit line 29 to control the flow of grit through the cavity 25. As shown, orbiting-mass oscillators 17 develop a wave pattern 33 that has a nodal point 35. Handles 37 extend from the support arm 15 at nodal point 35, since this is the place of minimum vibration. Thus the person utilizing and holding the device on the surface to be cleaned will feel very little of the vibratory effect.

The flexible elastomeric wall portion 21 can be sealed to the plate 13 by conventional adhesives. Alternatively, clamping arrangements can be provided to secure the wall portion where it is desirable to periodically remove it due to wear and the like. The flexible wall makes. it easy to move the device across the surface to be cleaned while substantially maintaining the grit within the chamber 25. There, of course, will be some loss of grit between the surface 23 being cleaned and the device 11, but this can normally be tolerated particularly when it is being replenished.

The wall 21, by having a high impedance, insures the necessary energy density within the volume 25 of the grit and prevents the transmission or transfer of substantial amounts of the energy from the plate 13 directly to the surface 23 being cleaned. In addition to rubber, other elastomeric materials including various plastics can be utilized, the main requirement being that they have a sufficiently high acoustic impedance to serve the function of the wallstructure 21 as above described.

In several embodiments of the invention, the grit is fed into the volume 25 through the inlet line 27 in the form of a slurry with water or other suitable liquid. This serves the function of easing the flow of the material through the volume 25 as well as cooling the vibratory area involved to prevent an excessive heat build up in the device. Another advantage of using a slurry is that the acoustic phenomenon known as cavitation can be achieved in the volume 25. It has been found that cavitation within a body of liquid, or even a condition approaching incipient cavitation, will greatly aid the cleaning function.

tional embodiment of the herein invention for particular utilization in the cleaning of cylindrical surfaces such as found in pipes. As shown in the figures, the device 41 comprises two half-cylindrical shells 43 and 45. Each half shell 43 and 45 is provided with a raised portion 47 and outwardly extending radial flange portions 49 and 51, respectively, about its diameter. Two rubber half rings 52 having an inner diameter equivalent to the outer diameter of the pipe 55 are'affixed to the flanges 49 and 51, respectively, of the shells 43 and 45 by adhesive bonding or the like. The shell 43 is then placed onthe pipe and shell 45 is held to shell 43 by bolts 54 attached to additional flanges 53. Thus a cavity 59 isformed between the raised portion 47 of the shell and the pipe 55, which cavity is then filled with grit through an entry line 61. The grit exits from the cavity 59 through an exit line 63. Additionally affixed to shell 43 is an orbiting-mass oscillator device 65, similar to that shown in US. Pat. No. 2,960,314 to the same inventor. Two cables 67 are attached tov the bolts 54 between the flanges 53 and serve to pull the device along the length of the pipe 55 to be cleaned.

The orbiting-mass oscillator 65 thus serves to vibrate the grit within the volume 59 in thesame manner as described in the embodiment shown in FIGS. 1 and 2. Once again, the elastomeric material 52 forming the seal between the shells 43 and 45 and the'pipe 55 provides both a good seal for the grit when in a slurry as well as preventing any dissipation of the vibratory energy directly into the pipe being cleaned.

I claim:

1. A device for cleaning surfaces with a cleaning grit material comprising:

a resonator plate in the form of a pair of half cylindrical shells; orbiting mass oscillator means connected to one of said shells for imparting sonic vibratory energy thereto at a frequency such as to cause resonant vibration of said device;

a high-acoustic-impedance material affixed to the other side of said plate forming a confining wall portion defining an enclosed volume when said cleaning material is brought into contact with the surface to be cleaned, and

means affixed to said resonator plate for flowing said cleaning material through said'enclosed volume.

2. A device for cleaning surfaces with a cleaning grit material comprising:

a resonator plate;

orbiting mass oscillator means connected to one side of said plate for imparting sonic vibratory energy thereto at a frequency such as to cause resonant vibration of sai d device; hlgh-acoustic-impeda'nce material affixed to the other side of said plate forming a confining wall portion defining an enclosed volume when said cleaning material is brought into contact with the surface tobe cleaned, and means affixed to said resonator plate for flowing said cleaning material through said enclosed volume, said surfaces to be cleaned being those of a cylindrical member, said plate being formed by a pair of half-cylindrical shells, each of said shells having a raised central portion and a pair of outwardly extending peripheral flange portions, said high acoustic impedance material comprising an elastomeric half. ring attached to each of said flange portions and means for holding said half shells to said cylindrical member with said high acoustic impedance material abutting against the.

surface of said member to form a pair of opposite walls thereabout, a cavity for retaining the cleaning material being formed between said walls, said shell and the surfaces of said cylindrical member.

3. The device of claim 2 wherein said means for flowing the cleaning material comprises an entry line fitted through the wall of one of said shells to provide a passageway for the material into said cavity and an exit line fitted through the wall of one of said shells to provide a passageway for drawing material out of said cavi- I 4. The device of claim .2 and further including cable means attached to said shells for pulling themalong the surface of the cylindrical member. 

1. A device for cleaning surfaces with a cleaning grit material comprising: a resonator plate in the form of a pair of half cylindrical shells; orbiting mass oscillator means connected to one of said shells for imparting sonic vibratory energy thereto at a frequency such as to cause resonant vibration of said device; a high-acoustic-impedance material affixed to the other side of said plate forming a confining wall portion defining an enclosed volume when said cleaning material is brought into contact with the surface to be cleaned, and means affixed to said resonator plate for flowing said cleaning material through said enclosed volume.
 2. A device for cleaning surfaces with a cleaning grit material comprising: a resonator plate; orbiting mass oscillator means connected to one side of said plate for imparting sonic vibratory energy thereto at a frequency such as to cause resonant vibration of said device; a high-acoustic-impedance material affixed to the other side of said plate forming a confining wall portion defining an enclosed volume when said cleaning material is brought into contact with the surface to be cleaned, and means affixed to said resonator plate for flowing said cleaning material through said enclosed volume, said surfaces to be cleaned being those of a cylindrical member, said plate being formed by a pair of half-cylindrical shells, each of said shells having a raised central portion and a pair of outwardly extending peripheral flange portions, said high acoustic impedance material comprising an elastomeric half ring attached to each of said flange portions and means for holding said half shells to said cylindrical member with said high acoustic impedance material abutting against the surface of said member to form a pair of opposite walls thereabout, a cavity for retaining the cleaning material being formed between said walls, said shell and the surfaces of said cylindrical member.
 3. The device of claim 2 wherein said means for flowing the cleaning material comprises an entry line fitted through the wall of one of said shells to provide a passageway for the material into said cavity and an exit line fitted through the wall of one of said shells to provide a passageway for drawing material out of said cavity.
 4. The device of claim 2 and further including cable means attached to said shells for pulling them along the surface of the cylindrical member. 